CONICET | Buscador de Institutos y Recursos Humanos

Escherichia coli O157:H7 is a Gram-negative pathogenic bacterium which is responsible for hemorrhagic colitis and the hemolytic uremic syndrome. This organism is recognized as an important cause of food-borne diseases reported in Argentina and other countries. The highly virulent nature of this bacterium demands a rigorous control of its dissemination in the environment to ensure food safety. Escherichia coli O157:H7 is producer of shiga toxins (Stx1 and/or Stx2) and has additional virulence factors. E. coli O157: H7 NCTC12900 is a natural atoxigenic strain isolated in 1992 in Austria. It is used as a model of study for biological safety reasons in different laboratory tests. The objective of this study was to characterize E. coli NCTC12900 in order to propose it as a model for meat studies. Its ability to grow in a meat model system (MMS), the presence of certain virulence genes (related to biofilm, attaching and effacing lesions) and its adhesion capacity to the meat extracellular matrix proteins (MEC) were evaluated. Meat growth capacity of NCTC 12900 was evaluated in MMS incubated at 25°C for 120 h. The viability was determined by cell counts on Mac Conkey agar. The presence of virulence and biofilm related genes were analyzed by PCR. The ability to bind to MEC proteins was assessed in vitro using microplates coated with collagen IV.E. coli presented an optimum growth in MMS, with a maximal of 8 log units at 24 h. PCR confirmed that NCTC 12900 possesses several virulence genes as well as the absence of genes related to toxins was confirmed. Adhesion tests suggest the ability to binding collagen IV.These findings propose E. coli NCTC12900, as a suitable pathogen to use in meat studies, since it grows in this niche, does not produce toxins but keeps other virulence genes. Its ability to bind MEC proteins guarantee meat colonization and is a key initial step in biofilm formation.Keywords: Enterohemorrhagic E. coli, meat, virulence factors, adhesion.